Automation tails from the fox hole

This post is part of the Learning GUI Toolmaking Series, here on FoxDeploy. Click the banner to return to the series jump page!

I got a lot of feedback last time, everyone wants the rest of the series, and you guys want it now! So I’m skipping my normal 1,000 word limit for this post and making this bad-boy LONG! There will still be a part three where I’ll show you how to use some of the trickier form elements. Some of them are absolute hacks to make them work in PowerShell, so if you’re the god of XAML and WPF, please have mercy on us mere-mortals and add some comments to let us know how I ought to be doing it.

Let’s jump back in and take our finished XAMl from last time and put it into PowerShell.

Whoa whoa, what’s XAML

I don’t know if you noticed this window. This whole time we’ve been adding elements, dropping boxes and text and things like that, it’s been updating in real time!

The language here is XAML, (Extensible Application Markup Language) which is a Microsoft language built on XML to make very small but effective applications easily. We’ll copy this code, but first, we need to make some changes to it before it will ‘just work’.

If you want to use my example as the base for your GUI, you can copy this right into Visual Studio:

Basically, we need to remove some properties from the window declaration, and also remove the x: before each name. But don’t do all of that by hand, just copy and paste it into this little blob I’ve made for you 🙂

Importing this into PowerShell

Updated January 2018 with better error catching!

If you’ve taken a look at the blog article on the MS site which I linked last week, some of the above might look very familiar. In fact, I’ve added a bit of extra output to help us in troubleshooting (by dumping a list of all of the variables relating to objects on our form) and made this into a snippet, which you can download and embed in your own ISE.

That’s a lot of code, but you only need to copy and paste your XAML from VisualStudio to PowerShell in between the here-string.

What’s a here-string?

If you’ve never heard of a here-string, it’s a programming term for a multi-line variable that maintains spacing and allows for variable expansion. Long-story short, it’s the @” “@ above.

When you’ve copied and pasted your XAML into the here-string above and hit F5 in the PowerShell ISE (or wherever you edit scripts), you’ll see the following:

Our tool has scanned through the GUI and created hooks associated with every interactable element on the screen. We can now make changes to these things with code, just by changing their objects. This little display here is actually a function embedded in the code. You can run it again later if you forget the variable names by running Get-FormVariables.

As you see above, if we want to run the GUI, we just type in

>$Form.ShowDialog() | Out-Null

That was SO EASY!

Changing values on the GUI is easy!

Now, what if we wanted to do something a bit more complex, like change the value of the Text where it says ‘TextBox’.

We need to hook into the properties that the tool displayed to us earlier. In this case, the name is $WPFTextBox. This is an object which this refers to the object on our form. That means we can change the text just by looking for a .text property on this object.

$WPFtextBox.Text
>TextBox

If we change this with a simple equals statement…

$WPFtextbox.Text = 'Hello World'

This is the basic flow we’ll take to interact with all of our GUIs hence-forth. Draw something cool in Visual Studio, copy and paste it into the snippet, then run Get-FormVariables and see what the name is for our new cool GUI features (they’re called ‘Form controls’ if we want to be specific). Then look at the new object and see what it’s properties and methods are.

But it doesn’t work…

One last thing before we fully upgrade this into an awesome tool, let’s try clicking the OK Button.

Nothing happens! Here’s why: by default, we need to give our button an action to run when we click it. You do this using the Add_Click() method, which lets us put a {script-block} into the () overload, which will be executed when the user clicks a button. This makes our buttons a great place to setup hooks if we want to grab the values from a box.

For instance, if we want our OK button to just close our form, we run this little number

$WPFbutton.Add_Click({$form.Close()})

After the form has closed, the value of all of these objects in the form still persist, so if the user made typed something like ‘YoDawg’ into our textbox, we can get it once the form is gone by running:

$WPFtextBox.Text

YoDawg

Alright, let’s make this into a WMI info gathering tool.

Building a better WMI tool

I’ve got a tool that I walk people through making in my Learning PowerShell bootcamp course (if you want me to come deliver one at your company, send me a message!), in which we learn how to query WMI/CIM and then expand from there and make it do cool fancy stuffs. The output of the tool at the end of the day looks like this.

We can make a GUI version of this by adding a ListView, which is pretty much embedding something like an Excel datasheet into this GUI. To do this, click ListView in the ToolBox and drag it to your form and size appropriately. You’ll notice that I also made a few tweaks to the layout to better fit what we want this tool to do.

You can just barely make it out, but there is a grid there now, waiting to receive our beautiful rows and columns. Let’s add some stuff, just a warning, this can be a bit tricky at first.

In Visual Studio, in the XAML, click the GridView Tag.

In properties on the right, click ‘Columns’

This will bring up the Column collection editor

Now, in this area, you’ll want to click the ‘Add’ button and change the width to about 100 for each, and specify the column name in the Header Box. I’ll add one each for each of the fields my tool returns:

• Drive Letter
• Drive Label
• Size(MB)
• FreeSpace%

As before, you can change the font by clicking on the area with text, then go to Properties>Text on the right side of the screen. When finished you should have something like this:

If we want to make our buttons and form actually work though, we’ll need to hook into the form again, as we did previously.

Making all of the new stuff work

If you want to catch up with where we are now in the walkthrough, get this stuff:

If you scroll to the bottom, just below Get-FormVariables, you’ll see an example of how to add data to a field. This part of our script is where the XAML has been parsed, and objects have been created to hook into them. This is where we’ll need to put our magic sauce to make the buttons and fields work and do cool things.

So, scroll down to the ‘Make the Objects Actually Work’ area.

First things first, take this snippet of code which accepts a computer name and returns the disk information:

If it breaks in a new way, I call that progress

Well, crap. Adding new rows worked, but now every column has the output for every property. This is happening because, very similar to when you work with the pipeline in PowerShell or make a function, you have to tell PowerShell how to bind to values.

To fix this, go up to your XAML for your GridView Columns and add a DisplayMemberBinding Property like this. Make sure if you’re deviating from the walkthrough and doing your own thing to pick names that make sense. If your name has a space in it, use single quotes around it.

And the finished product:

Whats up next?

Alright guys, I want to thank you for sticking with me to the end of this VERY long blog post. I hope you enjoy it and will use this technique to make some awesome GUIs of your own.

Join me for my post next time on this topic, part III in the GUI series, in which we dig into how to add some of the cooler and more difficult features to our GUI, like a tabbed interface (to get other WMI values) and how to use checkboxes and radio buttons, dropdown boxes and more!

Absolutely amazing guide. I am new to adding GUI’s to Powershell so i’m not so good at the moment!🙂

I have completed the script however the Get-Variable WPF* is not finding anything, and when i run the script without the ‘ ‘ between the show dialog at the bottom, I just get a blank iVision Azure Accelerator pop-up.

LOL, your first line says $inportXML, instead of $inputXML. 🙂 Once I changed that, I got some .net errors. These happen because PowerShell doesn’t support both the Click and TextChanged properties within XAML. You can do those (and I cover how to do them in later posts) but just not within XAML, so I removed them all. And it loads.

Looks pretty good to, very nice tool. Show this to your boss and demand a raise. The IT Best Practices forum gave a price of something like $60 per user interaction. Think of how much time your help desk will save with your new tool! Nicely done.

I’ve taken the advise and got it working again, but then i decided to try and jazz up the UI, and it doesn’t work again! Nice aye! I get –
“Exception calling ‘showdialog’ with ‘0’ argument(s): ‘ cannot set visibility or call show, showdialog, or windowinteropholper.ensurehandle after a window has close.”

ok I see it now. You should add a link to it at the bottom of the article! Also… I’m so happy I found this. I’m working on an app now. I’m still learning posh but i’m challenging myself and going to get it right. I want to know… is it possible to make it so a tab is only available when the actions of the second tab are complete? OR better yet… is there a way to make it so I can have a next button that bring the user to a new “slide” for lack of a better term?

Ok I see it now! You should add a link to it at the bottom of the article! Also… I’m so happy I found this. I’m working on an app now. I’m still learning posh but I’m challenging myself and going to get it right. I want to know… is it possible to make it so a tab is only available when the actions of the first tab are completed? OR better yet… is there a way to make it so I can have a next button that bring the user to a new “slide”/ “window” (for lack of a better term?) without having it open a separate window, rather, it just loads a new view on the same window?

Hello guys, how can I bring the window into the front, I tried different things like $Form.Activate() or $Form.IsActive=$true but nothing works.
I guess the solution is super easy!?
Please give me a tip.

thanks, but in my case its another thing, I just inserted Topmost=”True” in the xaml code. now it comes into the front BUT if I open a Out-GridView from the window, this Out-gridview will be displayed behind the window. is there a workaround?

Hello, I am really enjoying this tutorial that you have. Just what I have been looking for. I have become stuck with an error and I was wondering if you could assist me. Pretty much all my code is the same to your with the exception that I need to run my powershell in single threaded apartment or -sta mode since I am working on a Windows 7 64 bit with powershell 2.0. The code runs properly in powershell up to the point where I click the button. In which case my powershell throws out:

Hey man happy you like it. Would you mind posting your full code (remember to remove your company name or anything identifying) on paste bin or as a GitHub gist? Then post the link here. Don’t worry if it doesn’t appear in your post, I’ll see it and approve it

I have it execute a script block but i was wondering how i can have the output get displayed in the GIU.

I wrote a script to remotely decrypt BitLocker encrypted hard drives using Invoke-Command In powershell it works flawlessly, but i want to create a nicer looking tool for my end-users to use.

When i enter the computer name It runs the powershell script and freezes there until the drive is decrypted and closes (which is fine).
How can i make the GUI display the output of the powershell console?

Could use a little help myself. I’m new to Visual Studio but have some experience with PowerShell. What I’ve written is a form to allow a user to enter a username then click a search button to see if the user exists in Active Directory. This is for our HR department. It works on the initial search the way I intend it to but how do I refresh it so I can enter a new name to search for without having to rerun the script every time? Thanks.

For some reason it is not allowing me to reply to my older post. I did the change you suggested in my batch script but still ran into some issues. So I just gave in and updated my power shell to v.5.

Afterwards the script ran correctly within powershell, but when I attempted to run it through a batch script I ran into this error:
â?~Drive : The term ‘â?~Drive’ is not recognized as the name of a cmdlet,
function, script file, or operable program. Check the spelling of the name, or
if a path was included, verify that the path is correct and try again.

After some research, the cause for that error turned out to be the single quotation marks located here:
Get-WMIObject Win32_logicaldisk -ComputerName $computername | Select-Object @{Name=’ComputerName’;Ex={$computername}},`
@{Name=’Drive Letter’;Expression={$_.DeviceID}},`
@{Name=’Drive Label’;Expression={$_.VolumeName}},`
@{Name=’Size(MB)’;Expression={[int]($_.Size / 1MB)}},`
@{Name=’FreeSpace%’;Expression={[math]::Round($_.FreeSpace / $_.Size,2)*100}}

At drive letter, drive label, size(mb) and free space. For some reason it did not get those correctly so I just deleted and re-entered them. This part I copied from your script, so perhaps the browser changed the quotation marks to a different symbol.

Just found this and looks amazing! So tried right away but unfortunately I’m getting an error in Powershell ISE when loading my created example. Pastebin is https://pastebin.com/ryxqm8W6. I used Visual Studio Community 2017 to create the XAML. The error is due to line 55 with the xaml reader. Error message is “Exception calling “Load” with “1” argument(s): “Failed to create a ‘TextChanged’ from the text ‘textBox_TextChanged’.” Can you help please?

Has anyone else found a fix to the “Unable to load Windows.Markup.XamlReader. Double-check syntax and ensure .net is installed.”?
I have tried running -sta, and somewhere else I heard about removing some lines of the XAML:
xmlns:d=”http://schemas.microsoft.com/expression/blend/2008&#8243;
xmlns:mc=”http://schemas.openxmlformats.org/markup-compatibility/2006&#8243;
xmlns:local=”clr-namespace:MetLifePreflightChecker”
mc:Ignorable=”d”
I have tried both, but no luck.
I even went as far as to install .net 4.7 as that was the version I had on my dev box.
Apart from that, on the working development bow I have a great working program that took much less time to create than the Windows.System.Forms method.
Now if only it would work on a production machine..

would you say that there is an advantage using the Visual Studio IDE over the SAPIEN PrimalForms IDE? I have so far only used the Community Edition (which was free until a while ago) and I’m a programming n00b – yet I keep trying. But I would like to hear your opinion re. the environment to put the script together in.

probably a bit late to comment on this but i am in a bind. i get to the point where you paste the XAML data into the here string, but when i run the script it doesnt show the form variables. my XAML is from the 2017 edition of the community visual studio so i dont know if that whats causing the issue. heres my code via pastebin https://pastebin.com/Pqii5txQ if you are still able to help that would be awesome.

Hi! I look a look today and you ran into an issue I didn’t mention before. The method we use in this post depends on every item having a distinct name. Simply assign a name property for each element within the grid (your image, button, textblocks and label) by adding Name = ‘SomeName’ to each, and the code will work.

Found the errors, you have a ‘SelectionChanged’ property specified in one of your items, which PowerShell can’t handle. I added better error checking to catch this in the future though. Sorry for my late reply! Here’s the modified version. https://pastebin.com/YXEFUYNK

A million thanks for this awesome guide! This really saved my butt with a time-sensitive project (are there any other kind? lol). I’ve got one small issue, and I’m sure it’s just something simple I’m missing.

What I’m doing is searching a given directory for all EXE and DLL files and returning a table with the file name, description, and version number. It also exports the list to a TXT file in the c:\temp\ directory.

The issue I’m having is when I run it, the view in the GUI doesn’t seem to return anything, but the text file shows the info. What’s even stranger is in the table view in the GUI, a scroll bar appears and it looks like there are a bunch of blank entries in the table, almost like it’s returning it in invisible text.

I like it! I made two tweaks, namely adding a ‘\’ to the directory name, then I modified how you build a custom object by directly dereferencing .FileVersion, because a lot of .dll and .exe files won’t have that populated. Finally, I removed the `| format-table` command, because that was really the source of the trouble here. The Format- commands actually strip all file info and instead prepare a payload of console instructions (like ‘tab tab tab Name space space space File Description), and that’s why your bindings in the GridView wasn’t doing anything.

Also, just to let you know. None of your XAML code shows in any browser. Latest version of Chrome, Firefox and IE. This is across two PCs. Chrome has no add-ins installed (I don’t use it, only have it as a test/alternate browser). IE never gets opened unless I’m desparate (Which I am now). Not being able to see the XAML examples is severely hindering progress :(. Please help!

Its any of the tutorials. The lines are there (If I highlight, I can see how long each line of code should be). Its also being stripped from the boxes with both PoSH and XAML. PoSh is visible, XAML isn’t.